Corrosion inhibitors and compositions containing the same



Patented Get. 2;, 195% CORROSION INHIBITORS AND COMPOSITION CONTAININGTHE SAME Ellis K. Fields, Chicago, BL, and Roger W. Watson, Highland,Ind., assignors to Standard Oil Company, Chicago, 111., a corporation ofIndiana No Drawing. Application April 29, 195-3, Serial No. 352,036

22 Claims. (Cl. 252-32.7)

This invention relates to new compositions of matter which are effectivecorrosion inhibitors and which are noncorrosive to silver, silveralloysand similar metals. More particularly, the invention pertains tolubricant compositions containing the new compositions of matter whichare non-corrosive to such metals and inhibit the corrosion thereof bysulfur and/ or corrosive sulfur-containing compounds.

Advances in the design and construction of internal combustion enginesto produce improved and more eflicient and economical engines havepresented many problems in the lubrication of the modern internalcombustion engine. To meet the increased severe demands upon enginelubricants, many types of lubricant additives have been developed toobtain certain desired characteristics thereof. Among the more eifectiveaddition agents which have been developed for compounding withlubricants are many sulfur-containing Organic compounds, such as by wayof example, sulfurized terpenes, sulfurized hydrocarbon oils, vegetableoils or animal oils, xanthate esters, organic polysulfides, particularlypolyalkyl polysulfides, metal salts of organo-substituted thioacids ofphosphorus, metal salts of the reaction product of a phosphorus sulfideand a hydrocarbon, such as for example, polybutenes and otherpolyolefins, and combinations of the foregoing.

Recent increased use of silver and similar metal in the construction ofimproved internal combustion engines has created new problems in the useof sulfur-containing additives in lubricants for such engines; theprimary problem created being the corrosion of such silver parts of theengine by the sulfur-containing additives. While such corrosion can beeliminated by avoiding the use of sulfurcontaining additives inlubricants for such engines, this solution of the problem is accompaniedby the loss of the highly desired beneficial effects of the additives ofthis It is an object of the present invention to provide a noncorrosivecomposition of matter. Another object of'the invention is to provide acomposition non-corrosive to silver and similar metal. A still furtherobject of the invention is to provide a composition which will inhibitthe corrosion of silver and similar metal by sulfur and/or organosulfur-containing compounds. A still further object of the invention isto provide a lubricant composition which is non-corrosive. Still anotherobject of the invention is to provide a lubricant composition containingan addition agent which will inhibit the corrosion of silver and similarmetal by sulfur and/ or organo sulfur-containing compounds. A furtherobject of the invention is to provide a method of inhibiting thecorrosion of silver and .similar metal. Still another object of theinvention is to provide a method of lubricating internal combustionengines containing silver .and similar metal parts and inhibiting thecorrosion of such metals by lubricants which contain sulfur and/ororgano sulfur-containing compounds.

In accordance with the present invention, the new composition of matteris an oil-soluble reaction product of an aldehyde, a diarylamine and2,5-dimercapto-1,3,4-thiadiazole in the molar proportions of from about1:121 to 4:421, respectively, and preferably in the molar proportion of2:2:1, respectively. The resultant reaction products are believed tohave the general formula wherein R and R are the same or difierentaromatic radicals, and R" is hydrogen, or an alkyl or an aromaticradical.

The reaction can be carried out by adding the aldehyde to a mixture ofthe diarylamine or its derivative and the2,5-dimercapto-1,3,4-thiadiazole at a temperature of 25 C. to about C.,using, if desired, a suitable solvent, such as dioxane, Cellosolve,ethylene glycol, ethyl ethers and the like, to facilitate the reaction.The mixture is heated with stirring for a period of 10 minutes to 16hours, at the end of which time the reaction mixture is vfiltered andstripped of any solvent. Alternatively, the reaction mixture can bepoured into water and the reaction product separated, washed and driedby well-known suitable means.

The aldehyde can be an aliphatic or aromatic aldehyde of from 1 to 24carbon atoms or more, and may contain substituents such as alkoxy,hydroxy, mercapto, halogen, nitro, etc. groups. Examples of suitablealdehydes are formaldehyde, acetaldehyde, benzaldehyde, Z-ethylhexylaldehyde, butyraldehyde, heptaldehyde, caprylic aldehyde,vinylacetaldehyde, salicylaldehyde, etc.

The diarylamine or diarylarnine derivative employed is preferably onehaving 12 to about 44 carbon atoms; the diarylamine derivative can be analkylated diarylamine or a diarylamine or an alkylated diarylamine whichhas been reacted with sulfur. Suitable diarylamines and diarylaminederivatives are those having the general formulas R-S-R' in which R andR are monoor polycyclic or substituted monoor polycyclic aromatic rings.Diarylamines having substituted halogen, mercapto, alkoxy, nitro, etc.groups can be employed. The term diarylamine as used herein and in theappended claims includes compounds of formulas A and B. Examples ofsuitable diarylamines are diphenylamine, alpha, beta di-naphthylamine,phenyl naphthylamine, octylated diphenylamine, butylated diphenylamine,phenothiazine, naphthothiazine, alkylated phenothiazine, such asoctylated phenothiazine, etc.

Although it is not definitely known, it is believed that the principalreaction which takes place in the formation of these products may berepresented by the following equation:

wherein R1 and R2 represent aromatic groups and R represents hydrogen,alkyl or aromatic radicals.

The preparation of the above-described reaction products is illustratedby the following illustrative examples:

EXAMPLE I To a solution of 80 grams (0.4 mole) phenothiazine and 30grams (0.2 mole) 2,5-dimercapto-1,3,4-thiadiazole in 100 cc. dioxane,there were added, dropwise, at 60 C. over a 10-minute interval, 31 cc.(0.4 mole) 36% aqueous formaldehyde. The mixture was stirred at 95 C.for 4 hours, poured into Water, and the recovered green solid Washed anddried. The recovered reaction product contained 26% sulfur and 6.64%nitrogen.

EXAMPLE II To a solution of 66.7 grams (0.4 mole) diphenylamine and 30grams (0.2 mole) 2,5-dimercapto-1,3,4-thiadiazole in 100 cc. dioxane,there were added, dropwise, at 60 C. over a 30-minute interval, 31 cc.(0.4 mole) 36% aqueous formaldehyde. The mixture was heated at 95 C. for3 hours, and then stripped in vacuo. The recovered viscous red oil had asulfur content of 17.7% and a nitrogen content of 10.54%. Calculated forEXAMPLE III To a solution of 164 grams (0.4 mole) octylateddiphenylamine [(CaH1rCsH4)2NH] and 30 grams (0.2 mole)2,5-dimercapto-1,3,4-thiadiazole in 150 cc. dioxane, there were added,dropwise at 60 C. over a IS-minute interval, 31 cc. (0.4 mole) 36%aqueous formaldehyde. The mixture was heated at 95 C. for 3 hours,stripped in vacuo, and filtered. The recovered brown, glass-like solid,soluble in hexane, contained 8.9% sulfur and 6.14% nitrogen. Calculatedfor The above-described reaction products are effective corrosioninhibitors, particularly with respect to silver and similar metals whenused in combination with lubricant base oils, such as hydrocarbon oils,synthetic hydrocarbon oils, such as those obtained by the polymerizationof hydrocarbons, such as olefin polymers, for example, polybutenes,polypropylene and mixtures thereof, etc; synthetic lubricating oils ofthe alkylene-oxide type, for example, the Ucon oils, marketed by Carbideand Carbon Corporation, as well as other synthetic oils, such as thepolycarboxylic acid ester-type oils, such as the esters of adipic acid,sebacic acid, maleic acid, azelaic acid, etc. The herein-describedreaction products are effectively used in such lubricants inconcentrations of from about 0.02% to gbyout and preferably from about0.05% to about While the above-described reaction products can besuitably employed alone in combination with a base oil, they are usuallyused in combination with other lubricant addition agents, which impartvarious desired characteristics to the base oil. Usually, these reactionproducts are used in conjunction with detergent-type additives,particularly those which contain sulfur or phosphorus and sulfur. Theadditives of this type are usually used in amounts of from about 0.002%to about 10%, and preferably from about 0.01% to about 5%. Among thephosphorus and sulfur-containing addition agents are the neutralizedreactron products of a phosphorus sulfide, and a hydrocarbon, an alcoholand a ketone, an amine or an ester. Of the phosphorus sulfide reactionproduct additives, it is preferred to employ the neutralized reactionproducts of a phosphorus sulfide, such as phosphorus pentasulfide, and ahydrocarbon of the type described in U. S. 2,316,082, is-

sued to C. M. Loane et a1, April 6, 1943. As taught in this patent, thepreferred hydrocarbon constituent of the reaction is a mono-olefinhydrocarbon polymer resulting from the polymerization of low molecularweight mono-olefin hydrocarbons, such as propylenes, butenes, amylenesor copolymers thereof. Such polymers may be obtained by thepolymerization of mono-olefins of less than 6 carbon atoms in thepresence of a catalyst, such as sulfuric acid, phosphoric acid, boronfluoride, aluminum chloride, or other similar halide catalysts of theFriedel-Crafts type. 1

The polymers employed are preferably mono-olefin polymers or mixtures ofmono-olefin polymers and isomono-olefin polymers having molecularWeights ranging from about 150 to about 50,000, or more, and preferablyfrom about 500 to about 10,000. Such polymers can be obtained, forexample, by the polymerization in the liquid phase of a hydrocarbonmixture containing mono-olefins and isomono-olefins, such as butyleneand isobutylene at a temperature of from about F. to about F. in thepresence of a metal halide catalyst of the Friedel- Crafts type, such asfor example, boron fluoride, aluminum chloride, and the like. In thepreparation of these polymers, a hydrocarbon mixture containingisobutylene, butylenes and butanes recovered from petroleum gases,especially those gases produced in the cracking of petroleum oils in themanufacture of gasoline, can be used.

Another suitable polymer is that obtained by poly-- merizing in theliquid phase a hydrocarbon mixture comprising substantially Cahydrocarbons in the presence of an aluminum chloride-complex catalyst.The catalyst is preferably prepared by heating aluminum chloride withisooctane. The hydrocarbon mixture is introduced into the bottom of thereactor and passed upwardly through the catalyst layer, while atemperature of from about 50 F. to about F. is maintained in thereactor. The propane and other saturated gases pass through the catalystWhile the propylene is polymerized under these conditions. The propylenepolymer can be fractionated to any desired molecular weight, preferablyfrom about 500 to about 1000, or higher.

Other suitable polymers are those obtained by polymerizing a hydrocarbonmixture containing about 10% to about 25% isobutylene at a temperatureof from about 0 F. to about 100 F., and preferably 0 F. to about 32 F.in the presence of boron fluoride. After the polymerization of theisobutylene, together with a relatively minor amount of the normalolefins present, the reaction mass is neutralized, washed free of acidicsubstances and the unreacted hydrocarbons subsequently separated fromthe polymers by distillation. The polymer mixture so-obtained, dependingupon the temperature of reaction, varies in consistency from a lightliquid to viscous oily material and contains polymers having molecularweights ranging from about 100 to about 2000, or higher. The polymersso-obtained may be used as such, or the polymer may be fractionatedunder reduced pressure into fractions of increasing molecular Weights,and suitable fractions obtained reacted With the phosphorus sulfide toobtain the desired reaction products. The bottoms resulting from thefractionation of the polymer which may be Saybolt Universal viscositiesat 210 F. ranging from about 50 seconds to about 10,000 seconds, arewell suited for this purpose.

Essentially parafiinic hydrocarbons, such as bright stock residuums,lubricating oil distillates, petrolatums or paraffin waxes may be used.There can also be employed the condensation products of any of theforegoing hydrocarbons, usually through first halogenating thehydrocarbons, with aromatic hydrocarbons in the presence of anhydrousinorganic halides, such as aluminum chloride, zinc chloride, boronfluoride, and the like.

.Example of other high molecular weight olefinic hydrocarbons, which canbe employed,are cetene (C16), cerotene (C26), melene (C30), and mixedhigh molecular We ght alkenes obtained by cracking petroleum oils.

from about 13 to about'18 carbon atoms, and-preferably at least 15carbon atoms, are in a long chain. Such olefins can be obtained'by thedehydrogenation of parafiins, such as by cracking p arafiin Waxes or bythe dehalogenation of alkyl halides, preferably long chain alkylhalides, particularly halogenated parafiin waxes. 1 As. a startingmaterial there can be used the polymer or synthetic lubricating oilobtained by polymerizing unsaturated hydrocarbons resulting from thevapor phase cracking of, paraflin waxesin the presence of aluminumchloride which is fully described in U. S. Patents Nos. 1,955,260;1,970,402 and 2,091,398. Still another type of olefin polymer which maybe employed is the polymer resulting from the treatment of vapor phasecracked gasoline and/r gasoline fractions with sulfuric acid or solidabsorbents, such as fullers earth, whereby unsaturated polymerizedhydrocarbons are removed. The reaction products of the phosphorussulfide and thepolymers resulting from the voltolization of hydrocarbonsas de- :scribed, for example, in U. S. Patents Nos. 2,197,-768 and2,191,787 are also suitable.

Other hydrocarbons that can be reacted with a phosphorus sulfide arearomatic hydrocarbons, such as for example, benzene, naphthalene,toluene, zylene, diphenyl, and the like, or an alkylated aromatichydrocarbon, such as for example, benzene having an alkyl substituenthaving at least four carbon atoms, and preferably at least eight carbonatoms, such as a long chain paraffin wax.

The phosphorus sulfide-hydrocarbon reaction product can be readilyobtained by reacting a phosphorus sulfide, for example, P25 with thehydrocarbon at a temperature of from about 200 F. to about 500 F., andpreferably from about 200 F. to about 400 F., using from about 1% toabout 50%, and preferably from about 5% to about 25% of the phosphorussulfide in the reaction. .It is advantageous to maintain a non-oxidizingatmosphere, s'uch as forexample, an atmosphere of nitrogen above thereaction mixture. Usually, it is preferable to use an amount of thephosphorus sulfide that will completely react with the hydrocarbon sothat no further purification becomes necessary; however, an excessamount of phosphorus sulfide can be used and separated from the productby filtration or by dilution with a hydrocarbon solvent, such as hexane,filtering and subsequently removing the solvent by suitable means, suchas by distillation. If desired, the reaction product can be furthertreated with steam at an elevated temperature of from about 100 F. toabout 600 F.

' The phosphorus sulfide-hydrocarbon reaction product normally shows atitratable acidity which is neutralized by treatment with a basicreagent. The phosphorus sulfide-hydrocarbon reaction product, whenneutralized with a basic reagent containing a metal constituent, ischaracterized by the presence or retention of the metal constituent ofthe basic reagent.

The neutralized phosphorus sulfide-hydrocarbon reaction product can beobtained by treating the acidic reaction product with a suitable basiccompound, such as hydroxide, carbonate, oxide or sulfide of an alkalineearth metal or an alkali metal, such as for example, potassiumhydroxide, sodium hydroxide, sodium sulfide, calcium oxide, lime, bariumhydroxide, barium oxide, etc. Other basic reagents can be used, such asfor example, ammonia or an alkyl or aryl-substituted ammonia, such asamines. The neutralization of the phosphorus sulfidehydrocarbon reactionproduct is carried out preferably in a non-oxidizing atmosphere bycontacting the acidic reaction product either as such or dissolved in asuitable solvent, such as naphtha with a solution of the basic agent. Asan alternative method, the reaction product can be treated with solidalkaline compounds, such as KOH, NaOH, NazCOa, K2CO3, CaO, BaO,Ba(OI-I)2,

NazS, and the like, at an elevated temperature of from aboutl00 F. toabout 600 F. Neutralized reaction products containing a heavy metalconstituent, such. as for example, tin, titanium, aluminum, chromium,cobalt, zinc, iron, and the like, can be obtained by reacting a salt ofthe desired heavy metal with the phosphorus sulfide-hydrocarbon reactionproduct which has. been treated with a basic reagent, such asabove-described.

Other phosphorus sulfide-reaction products whichcan be used are thereaction products of a phosphorus sulfide and a fatty acid ester of thetype described in U. S. 2,399,243; the phosphorus sulfide-degrasreaction prodnets of U. S. 2,413,332; the reaction product of analkylated phenol with the condensation product of P285 and turpentine ofU. S. 2,409,877 and U. S. 2,409,878; the reaction product of aphosphorus sulfide and stearoni trile of U. S. 2,416,807, etc. i v

The silver corrosion inhibiting property of the above describeddimercapto-thiadiazole reaction products is demonstrated by the data inTable I, which were obtained by subjecting mixtures of hydrocarbon oil,a neutralized reaction product of P2S5 and a polybutene, and various2,5-dimercapto-1,3,4-thiadiazole reaction products to the followingtest, hereinafter referred to as the modified E. M. D. Test:

A silver strip 2 cm. x 5.5 cm. with a small hole at one end forsuspension, is lightly abraded with No. 0 steel wool, wiped free of anyadhering steel wool, washed with carbon tetrachloride, air-dried andthen weighed to 0.1 milligram. 300 cc. of the oil to be tested is placedin a 500 cc. .lipless glass beaker and the oil heated to .a temperatureof 300 F. (:L-2 F.) and the silver test strip suspended in the oil sothat the strip is completely inimersed therein. The oil in the beaker isstirred by means of a glass stirrer operating at 300 R. P. M. At the endof twenty-four hours, the silver strip is removed and while still hotrinsed thoroughly with carbon tetrachloride and air-dried. The silverstrip is then immersed in a 10% potassium cyanide solution at roomtemperature until the silver surface assumes its original bright orsilver appearance, then washed successively with distilled water andacetone, air-dried and weighed.

The following lubricant compositions were subjected to the above testand the results obtained tabulated in Table 1:

Sample A.-Control (solvent extracted SAE- oil+3.3% barium-containingneutralized reaction prodnet of P255 and polybutene of about 1000molecular weight.)

Sample B.--A[-.75% product of Example III.

Table I I Silver corrosion Sample No: (Wt. loss in mg.) A 20 Sinceaweight loss of less than 20 milligrams is desirable, the ability of the2,5-dirnercapto 1,3,4-thiadizole derivatives of this invention toinhibit the corrosion of silver is demonstrated by the above data.

The effectiveness of the herein-described thiadiazole reaction productsin inhibiting corrosion toward copper and/ or lead-containing metals,such as for example, copper-lead alloys, is demonstrated by the data inTable II, obtained by subjecting the above Samples A and B to thefollowing test:

A copper-lead test specimen is lightly abraded with steel wool, washedwith naphtha, dried and weighed to the nearest milligram. The cleanedcopper-lead test specimen is suspended in a steel beaker, cleaned with ahot tri-sodium phosphate solution, rinsed with water, acetone and dried,and 250 grams of the oil to be tested, together with 0.625 gram leadoxide and grams of a 30-35 mesh sand charged to the beaker. The beakeris then placed in a bath or heating .block and heated to a temperatureof 300 F- :2 F.) while the contents are stirred by means of a stirrerrotating'at 750 R; P. M. The contents of theb'eaker are maintained atthis temperature for twenty-four hours, after which the copper-lead testspecimen is removed,: rinsed with naphtha, dried :and

i i andan additional 0.375 gram of lead oxide added to the weighed. Thetest specimen is then replacedin' the'beaker test oil. -At the end of anadditional twenty-four hours of test operation the test specimen isagain removed,

. i rinsed and dried as before, and weighed. The test speci-. men isagain placed in the beaker, together with an additional 0.250 gram -oflead oxide, and the test con- 7 tinned for another twenty-fourhours(seventy-two hours total). Atthe conclusion of. this time, the testspecimen .is removed from the beaker, rinsed in naphtha,'dried andweighed.

-The loss in weight of the test specimen is recorded after eachweighing. I

: I This test known as the Stirring Sand Corrosion Test, is

- referred to hereinafter asS.' S. C.- T.." I

Since weightlosses of 200 milligrams. in 48- hours and 500 milligrams in72 hours are allowable, the copper-lead inhibiting property of theherein-described 2,5-dimer-' I capto.-1,3,4-th.iadizole derivatives is'clearlyfiemonstrated cant. compositions elemental sulfur or an organicsulfur: containing compound of the type hereinabove described I bythejabove data.

Under certain conditions it is desirable to use in lubrieither alone orin combination with other additives. Ef-

fective lubricant compositions are obtained by the combination of theneutralized reaction products of a phosphorus sulfide and a hydrocarbon,as above-described, with elemental sulfur, or an organicsulfur-containing compound, such as sulfurized mineral oils, sulfun'zednondrying animal and vegetable oils, sulfurized olefins and olefinpolymers, sulfurized sperm oil, etc., as described and claimed in U. S.Reissue 22,464 issued to C. D. Kelso et a1. April 4, 1944, or withsulfurized terpenes, for example, dipentene as described and claimed inU. S. 2,422,585 issued to T. H. Rogers et al. June 17, 1947. While thesecompounds impart highly desired characteristics to lubricants, andeffectively inhibit the corrosion of copper and/or lead, they arecorrosive to silver and similar metals, and for this reason, lubricantscontaining such addition agents fail to pass the above-described E. M.D. test. -In accordance with the present invention, however, theincorporation in such lubricant compositions of small amounts, namely,from about 0.1% to about 10%, and preferably from about 0.25% to about5% of the hereindescribed 2,5-dimercapto-1,3,4-thiadizole reactionproducts, effectively inhibits the corrosiveness of the silver corrosivecompounds without impairing their other desired properties.

The ability of the herein-described 2,5-dimencapto- 1;3,4-thiadiazolederivatives to inhibit the silver corrosion tendency of activesulfur-containing organic compounds is demonstrated by the following E.M. D. data in Table III, obtained with the following compositions:

Sample A .--Control (solvent-extracted SAE- Oil-{- 3.3%barium-containing neutralized reaction product of P285 and a polybuteneof about 1000 molecular weight+0.75% sulfurized dipentene.)

Sample B .--A +0.15% product of Example I. .Safnple C .A +0.15% productof Example Table III X Silver corrosion Sample No.: '(mg. weight loss) A.100 r B ,4

2,5-dimercapto-1,3,4-thiadiazo1e derivatives effectively inhibitcorrosion tendencies of active sulfur-containing or-' I Iganiccompounds, i; e.,.sulfurized terpenes toward silver.

Although the invention has been described in connection with the use ofthe herein-described 2,5.-dimercapto-' 1,3,4-thiadiazole derivativesincombination with the. one or; more secondary. additives in. lubricantcompositions, the invention is not restrictedto such use, since:these'derivatives find utility'when. used alone in various lubricant.

' compositions or hydrocarbon oil compositions to impart improved anddesired characteristics thereto. For example, they areeifectiveininhibiting the oxidation of hy-- 'droca-rbon oilsasdemonstratedby the data in Table IV,

. which were obtained by subjecting a hydrocarbon turbine oil containing0.1% of the product of Example III to the test method described in ASTMmethod D943+47T and determining the number of hours required for the oilun I i dergoing the test to develop acidity equivalent to 2 milligramsKOH pergramof oil. The time required to 'develop this acidity-is calledthe Life of the oil.

Table IV Lifeno. hours 1. Control-No additive 5075 2. Control+0.1%Product of Example HI 1770 In addition to the aforementioneddetergent-type additives and corrosion inhibitors,compositions'containing the herein-described Y derivatives thiadiazolecan contain other additives, "such an anti oxi- Q dants, pour-pointdepressors, extreme pressure agents,

; anti-wear agents, V. I. improvers, etc.

While this-invention has been described-inconnection I with the use ofthe herein-described additives and lubricant compositions, their use isnot limited thereto; but the same can be used in products other thanlubricating oils, such as for example, fuel oils, insulating oils,greases, non-drying animal and vegetable oils, waxes, asphalts, and anyfuels for internal combustion engines, particularly where sulfurcorrosion must be combatted.

Concentrates of a suitable oil base containing more than 10% for exampleup to 50% or more, of the hereindescribed thiadiazole derivatives aloneor in combination with more than 10% of the detergent-type additiveand/or other additives, can be used for blending with hydrocarbon oilsor other oils in the proportions desired for the particular conditionsof use to give a finished product containing from 0.02% to about 10% ofthe thiadiazolederivative.

Percentages given herein and in the appended claims are weightpercentages unless otherwise stated.

Although the present invention has been described with reference tospecific preferred embodiments thereof, the invention is not to beconsidered as limited thereto but includes Within its scope suchmodifications and variations as come within the spirit of the appendedclaims.

We claim:

1. A new composition of matter, the reaction product of an aromaticnitrogen compound selected from the class consisting of athiodiarylamine and a diarylamine, an aldehyde having from 1 to about 24carbon atoms and 2,5-dirnercapto-1,3,4-thiadiazole, said reactionproduct having anti-oxidant and corrosion inhibiting properties andbeing suitable for addition to oils to impart oxidation and corrosioninhibiting characteristics thereto, said reactants being reacted in themolarproportions of from about 121:1 to 4:4:1, respectively, at atemperature of from 25 C. to about C.

' 1 7 I As indicated by the above data, the herein'described 2. Acomposition of matter as described in claim 1 in which the aldehyde isan aliphatic aldehyde of from 1 to about 24 carbon atoms.

3. A composition of matter as described in claim 2 in which thealiphatic aldehyde is formaldehyde.

4. A composition of matter as described in claim 2 in which thealiphatic aldehyde is 2-ethylhexyl aldehyde.

5. A composition of matter as described in claim 1 in which the aldehydeis an aromatic aldehyde.

6. A composition of matter as described in claim 5 in which the aromaticaldehyde is benzaldehyde.

7. A composition of matter as described in claim 1 in which thediarylamine is diphenylamine.

8. A composition of matter as described in claim 1 in which thediarylamine is an alkylated diarylamine.

9. A composition of matter as described in claim 8 in which thealkylated diarylamine is octyl diphenylamine.

10. A composition of matter as described in claim 1 in which thediarylamine is phenothiazine.

11. A composition comprising a major proportion of an oleaginouscompound and from about 0.02% to about 10% of an oil-soluble reactionproduct of an aromatic nitrogen compound selected from the classconsisting of a thiodiarylamine and a diarylamine, an aldehyde havingfrom 1 to about 24 carbon atoms, and 2,5-dimercapto- 1,3,4-thiadiazole,said reactants being reacted in the molar proportions of from about1:1:1 to 4:4:1, respectively, at a temperature of from 25 C. to about100 C.

12. A composition as described in claim 11 in which the aldehyde is analiphatic aldehyde of 1 to about 24 carbon atoms.

13. A composition as described in claim 11 in which the aldehyde isformaldehyde.

14. A composition as described in claim 11 in which the diarylamine isan alkylated diarylamine.

15. A composition as described in claim 11 in which the diarylamine isoctyl diphenylamine.

16. A composition comprising a major proportion of a hydrocarbon oil,from about 0.02% to about 10% of an oil-soluble reaction product of analdehyde having from 1 to about 24 carbon atoms, an aromatic nitrogencompound selected from the class consisting of a thiodiarylamine and adiarylamine and 2,5-dimercapto-1,3,4-thiadiazole, said reactants beingreacted in the molar ratio of from 11121 to about 4:4: 1, respectively,at a temperature of from 25 C. to about 100 C., and from about 0.001% toabout 10% of a sulfur-containing organic compound normally corrosive tosilver.

17. A composition as described in claim 16 in which 10 thesulfur-containing organic compound is a sulfurized terpene.

18. A lubricant composition comprising a major proportion of alubricating oil, from about 0.001% to about 10% of a phosphorus andsulfur-containing detergenttype lubricant additive, and from about 0.02%to about 10% of an oil-soluble reaction product of an aldehyde havingfrom 1 to about 24 carbon atoms, an aromatic nitrogen compound selectedfrom the class consisting of a thiodiarylamine and a diarylamine and2,5-dimercapto- 1,3,4-thiadiazole, said reactants being reacted in molarratios of from 1:1:1 to about 4:4:1, respectively at a temperature offrom 25 C. to about C.

19. A lubricant composition as described in claim 18 in which thedetergent-type additive is a neutralized re action product of aphosphorus sulfide and a hydrocarbon.

20. A lubricant composition as described in claim 19 in which thehydrocarbon is a polybutene.

21. An addition agent for lubricant compositions comprising aconcentrated solution of a hydrocarbon oil containing more than 10% ofan oil-soluble reaction product of an aldehyde having from 1 to about 24carbon atoms, an aromatic nitrogen compound selected from the classconsisting of a thiodiarylamine and a diarylamine and2,5-dimercapto-1,3,4-thiadiazole, said reactants being reacted in molarratios of from about 1:1:1 to 4:4:1, respectively, at a temperature offrom 25 C. to about 100 C., said solution being capable of dilution witha hydrocarbon oil to form a homogenous mixture containing from about0.02% to about 10% of said oilsoluble reaction product.

22. The method of inhibiting the corrosion of silver by an oleaginouscomposition containing an active sulfurcontaining organic compoundnormally corrosive to silver, comprising incorporating in saidoleaginous composition an oil-soluble reaction product of an aldehydehaving from 1 to about 24 carbon atoms, an aromatic nitrogen compoundselected from the class consisting of a thiodiarylamine and adiarylamine and 2,5-dimercapto-l,3,4- thiadiazole, said reactants beingreacted in molar ratios of from about 1:1:1 to 4:4:1, respectively, at atemperature of from 25 C. to about 100" C., said reaction product beingused in small but suflicient quantities to inhibit said corrosion.

References Cited in the file of this patent Zur Chemie des2,5-Dimercapto-1,3,4-thiodiazols, article in Monatshefte fiir Chemie,vol. 81, pages 848 and 849.

1. A NEW COMPOSITION OF MATTER, THE REACTION PRODUCT OF AN AROMATICNITROGEN COMPOUND SELECTED FROM THE CLASS CONSISTING OF ATHIODIARYLAMINE AND A DIARYLAMINE, AN ALDEHYDE HAVING FROM 1 TO ABOUT 24CARBON ATOMS AND 2,5-DIMERCAPTO-1,3,4-THIADIAZOLE, SAID REACTION PRODUCTHAVING ANTI-OXIDANT AND CORROSION INHIBITING PROPERTIES AND BEINGSUITABLE FOR ADDITION TO OILS TO IMPART OXIDATION AND CORROSIONINHIBITING CHARACTERISTICS THERETO, SAID REACTANTS BEING REACTED IN THEMOLAR PORPORTIONS OF FROM ABOUT 1:1:1 TO 4:4:1, RESPECTIVELY, AT ATEMPERATURE OF FROM 25* C. TO ABOUT 100* C.
 11. A COMPOSITION COMPRISINGA MAJOR PROPORTION OF AN OLEAGINOUS COMPOUND AND FROM ABOUT 0.02% TOABOUT 10% OF AN OIL-SOLUBLE REACTION PRODUCT OF AN AROMATIC NITROGENCOMPOUND SELECTED FROM THE CLASS CONSISTING OF A THIODIARYLAMINE AND ADIARYLAMINE, AN ALDEHYDE HAVING FROM 1 TO ABOUT 24 CARBON ATOMS, AND2,5-DIMERCAPTO1,3,4-THIADIAZOLE, SAID REACTANTS BEING REACTED IN THEMOLAR PROPORTIONS OF FROM ABOUT 1:1:1 TO 4:4:1, RESPECTIVELY, AT ATEMPERATURE OF FROM 25* C. TO ABOUT 100* C.